Amorphous fluoropolymers are a class of plastic materials with low surface energy and low dielectric constant that are characterized as exceptionally chemically inert and thermally stable due to their strong carbon-fluorine and carbon-carbon bonds. Most of these polymers have low reflective index with high transparency in a wide range of wavelength from 200 to 2000 nm. Amorphous fluoropolymers are widely used in different fields such as coatings in optics, insulators in electronics, protection material in chemical industries, and semiconductors. [1]
Applying amorphous fluoropolymers in nano devices is in high demand for many emerging high-tech applications; especially in pharmaceutical products, and electronics. So far, all currently available techniques to pattern amorphous fluorinated polymers are based on etching by high energy radiation sources, such as focused laser light, resulting in micro structures with aspect ratios less than 2; synchrotron radiation, giving micro structures which reach aspect ratios between 10 and 70; focused ion beams, with 5 nm spatial resolution. In addition, high doses of electron beam radiation have been reported to cause photodegradation of the polymer with ˜200 nm feature resolution. [2-4]
However, lithography-based nano-patterning of fluorinated polymers still remains a challenge, mainly because of the chemical inertness. No suitable solvents to chemically etch, or develop this type of polymer have been reported.
The method presented here is a novel approach to achieve patterning of fluoropolymer surfaces with micrometer and submicrometer feature resolution by means of chemically developing surface-deposited and high-energy radiation exposed films of such polymers in the fashion of a negative lithographic resist process.